Abstract The goal of the Pathology Core is to provide professional services and expertise to Investigators of the ?Gene Therapy for Cystic Fibrosis Lung Disease? Program Project. To facilitate these goals the Pathology Core offers 1) technical expertise and support for histotechnology techniques from tissue processing to specialized staining (histochemical and immunohistochemical) and 2) ACVP-boarded veterinary pathologist expertise and support for morphologic, quantitative and semi-quantitative evaluation of tissues (e.g. sinus and lung) from CF pig and CF ferret studies. The Pathology Core will provide services to Program Investigators in a timely and efficient manner for optimal assessment of tissues. The Specific Aims of the Pathology Core are: 1) Provide scientific support and expertise to Program Investigators for Histology and Veterinary Pathology applications. 2) Apply quantitaive, semi-quantitative, and morphologic (e.g. cell type) techniques to assess CFTR or reporter gene expression in cell types following vector delivery (e.g. AAV, lentivirus, adenovirus ? Projects 1, 3) using CFTR or reporter (e.g. GFP, mCherry) detection methods such as immunohistochemistry and fluorescence microscopy. 3) Apply quantitative, semi-quantitative, and morphologic techniques to assess changes in disease state of sinus or lung following CFTR expression from gene transfer vectors (Projects 1, 3) or transgenic expression of CFTR in CF pigs and ferrets (Projects 2, 3).